Wireless power for charging devices

ABSTRACT

Exemplary embodiments are directed to wireless power. A host device peripheral may comprise a wireless power charging apparatus, which may include transmit circuitry and at least one antenna coupled to the transmit circuitry. The at least one antenna may be configured to wirelessly transmit power within an associated near-field region. Additionally, the host device peripheral may be configured to couple to a host device.

CLAIM OF PRIORITY UNDER 35 U.S.C. §119

This application claims priority under 35 U.S.C. §119(e) to:

U.S. Provisional Patent Application 61/150,302 entitled “WIRELESS POWERCHARGER IN A PORTABLE DEVICE” filed on Feb. 5, 2009, the disclosure ofwhich is hereby incorporated by reference in its entirety;

U.S. Provisional Patent Application 61/150,254 entitled “WIRELESS POWERACCESSORY” filed on Feb. 5, 2009, the disclosure of which is herebyincorporated by reference in its entirety;

U.S. Provisional Patent Application 61/229,218 entitled “POWERMANAGEMENT FOR WIRELESS CHARGING” filed on Jul. 28, 2009, the disclosureof which is hereby incorporated by reference in its entirety;

U.S. Provisional Patent Application 61/229,664 entitled “CHARGING MODULEACCESSORY” filed on Jul. 29, 2009, the disclosure of which is herebyincorporated by reference in its entirety; and

U.S. Provisional Patent Application 61/235,660 entitled “DEPLOYABLEWIRELESS POWER CHARGING SYSTEM” filed on Aug. 20, 2009, the disclosureof which is hereby incorporated by reference in its entirety.

BACKGROUND

1. Field

The present invention relates generally to wireless charging, and morespecifically to charging devices including portable charging devices andpower management for charging devices.

2. Background

Typically, each battery powered device requires its own charger andpower source, which is usually an AC power outlet. This becomes unwieldywhen many devices need charging.

Approaches are being developed that use over the air power transmissionbetween a transmitter and the device to be charged. These generally fallinto two categories. One is based on the coupling of plane waveradiation (also called far-field radiation) between a transmit antennaand receive antenna on the device to be charged which collects theradiated power and rectifies it for charging the battery. Antennas aregenerally of resonant length in order to improve the couplingefficiency. This approach suffers from the fact that the power couplingfalls off quickly with distance between the antennas. So charging overreasonable distances (e.g., >1-2 m) becomes difficult. Additionally,since the system radiates plane waves, unintentional radiation caninterfere with other systems if not properly controlled throughfiltering.

Other approaches are based on inductive coupling between a transmitantenna embedded, for example, in a “charging” mat or surface and areceive antenna plus rectifying circuit embedded in the host device tobe charged. This approach has the disadvantage that the spacing betweentransmit and receive antennas must be very close (e.g. mms). Though thisapproach does have the capability to simultaneously charge multipledevices in the same area, this area is typically small, hence the usermust locate the devices to a specific area.

A need exists for portable charging devices configured for coupling toan electronic device. Further, there exists a need for electroniccharging devices configured for convenient placement of electronicdevices to enable for providing wireless power thereof. A need alsoexists for a charging device configured to detect the presence of anelectronic device while in a power saving mode.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a simplified block diagram of a wireless power transfersystem.

FIG. 2 shows a simplified schematic diagram of a wireless power transfersystem.

FIG. 3 shows a schematic diagram of a loop antenna for use in exemplaryembodiments of the present invention.

FIG. 4 is a simplified block diagram of a transmitter, in accordancewith an exemplary embodiment of the present invention.

FIG. 5 is a simplified block diagram of a receiver, in accordance withan exemplary embodiment of the present invention.

FIG. 6 shows a simplified schematic of a portion of transmit circuitryfor carrying out messaging between a transmitter and a receiver.

FIG. 7 illustrates a charging device having at least one transmitantenna positioned adjacent a surface thereof, in accordance with anexemplary embodiment of the present invention.

FIG. 8 is another depiction of the charging device of FIG. 7, includingat least one transmit antenna positioned adjacent another surfacethereof, according to an exemplary embodiment of the present invention.

FIG. 9 is yet another depiction of the charging device of FIGS. 7 and 8,having at least one transmit antenna positioned adjacent yet anothersurface thereof, according to an exemplary embodiment of the presentinvention.

FIG. 10 illustrates a charging device having an electronic devicepositioned thereon, according to an exemplary embodiment of the presentinvention.

FIG. 11 illustrates a charging device having an electronic deviceattached thereto, in accordance with an exemplary embodiment of thepresent invention.

FIG. 12 illustrates a charging device having a pocket and an electronicdevice positioned therein, in accordance with an exemplary embodiment ofthe present invention.

FIG. 13 illustrates another charging device having an electronic devicepositioned thereon, according to an exemplary embodiment of the presentinvention.

FIGS. 14 and 15 illustrate a charging device comprising a charging pad,according to an exemplary embodiment of the present invention.

FIGS. 16 and 17 illustrate a charging system comprising an electronicdevice and a charging pad, in accordance with an exemplary embodiment ofthe present invention.

FIG. 18 illustrates a portable wireless power device, according to anexemplary embodiment of the present invention.

FIG. 19 illustrates a system including an electronic device and aportable wireless power device, according to an exemplary embodiment ofthe present invention.

FIG. 20 illustrates a system including a portable wireless power devicepositioned within an electronic device, in accordance with an exemplaryembodiment of the present invention.

FIG. 21 illustrates a system including a wireless transmit antennaproximate a portable wireless power device positioned within anelectronic device, in accordance with an exemplary embodiment of thepresent invention.

FIG. 22 illustrates a system including a wireless transmit antennaproximate a portable wireless power device, in accordance with anexemplary embodiment of the present invention.

FIG. 23 illustrates a system including a portable wireless power devicehaving a portion deployed from an electronic system, in accordance withan exemplary embodiment of the present invention.

FIG. 24 illustrates a system including a portable wireless power devicecoupled to an external power source and having a portion deployed froman electronic system with an electronic device positioned thereon, inaccordance with an exemplary embodiment of the present invention.

FIG. 25 illustrates a system including a portable wireless power deviceproximate a transmit antenna and having a portion deployed from anelectronic system with an electronic device positioned thereon,according to an exemplary embodiment of the present invention.

FIG. 26 illustrates a system including a portable wireless power devicepositioned within an electronic device having a portion deployed fromthe electronic system with an electronic device positioned thereon, inaccordance with an exemplary embodiment of the present invention.

FIG. 27 illustrates a portable wireless power device having anelectronic device positioned thereon, according to an exemplaryembodiment of the present invention.

FIG. 28 illustrates a wireless transmit antenna proximate a portablewireless power device having an electronic device positioned thereon, inaccordance with an exemplary embodiment of the present invention.

FIG. 29 is a flowchart illustrating a method, in accordance with anexemplary embodiment of the present invention.

FIG. 30 illustrates a state machine diagram for a charging device,according to an exemplary embodiment of the present invention.

FIG. 31 illustrates another state machine diagram for a charging device,in accordance with an exemplary embodiment of the present invention.

FIG. 32 is a flowchart illustrating another method, in accordance withan exemplary embodiment of the present invention.

DETAILED DESCRIPTION

The word “exemplary” is used herein to mean “serving as an example,instance, or illustration.” Any embodiment described herein as“exemplary” is not necessarily to be construed as preferred oradvantageous over other embodiments.

The detailed description set forth below in connection with the appendeddrawings is intended as a description of exemplary embodiments of thepresent invention and is not intended to represent the only embodimentsin which the present invention can be practiced. The term “exemplary”used throughout this description means “serving as an example, instance,or illustration,” and should not necessarily be construed as preferredor advantageous over other exemplary embodiments. The detaileddescription includes specific details for the purpose of providing athorough understanding of the exemplary embodiments of the invention. Itwill be apparent to those skilled in the art that the exemplaryembodiments of the invention may be practiced without these specificdetails. In some instances, well-known structures and devices are shownin block diagram form in order to avoid obscuring the novelty of theexemplary embodiments presented herein.

The words “wireless power” is used herein to mean any form of energyassociated with electric fields, magnetic fields, electromagneticfields, or otherwise that is transmitted between from a transmitter to areceiver without the use of physical electromagnetic conductors.

FIG. 1 illustrates a wireless transmission or charging system 100, inaccordance with various exemplary embodiments of the present invention.Input power 102 is provided to a transmitter 104 for generating aradiated field 106 for providing energy transfer. A receiver 108 couplesto the radiated field 106 and generates an output power 110 for storingor consumption by a device (not shown) coupled to the output power 110.Both the transmitter 104 and the receiver 108 are separated by adistance 112. In one exemplary embodiment, transmitter 104 and receiver108 are configured according to a mutual resonant relationship and whenthe resonant frequency of receiver 108 and the resonant frequency oftransmitter 104 are very close, transmission losses between thetransmitter 104 and the receiver 108 are minimal when the receiver 108is located in the “near-field” of the radiated field 106.

Transmitter 104 further includes a transmit antenna 114 for providing ameans for energy transmission and receiver 108 further includes areceive antenna 118 for providing a means for energy reception. Thetransmit and receive antennas are sized according to applications anddevices to be associated therewith. As stated, an efficient energytransfer occurs by coupling a large portion of the energy in thenear-field of the transmitting antenna to a receiving antenna ratherthan propagating most of the energy in an electromagnetic wave to thefar field. When in this near-field a coupling mode may be developedbetween the transmit antenna 114 and the receive antenna 118. The areaaround the antennas 114 and 118 where this near-field coupling may occuris referred to herein as a coupling-mode region.

FIG. 2 shows a simplified schematic diagram of a wireless power transfersystem. The transmitter 104 includes an oscillator 122, a poweramplifier 124 and a filter and matching circuit 126. The oscillator isconfigured to generate at a desired frequency, which may be adjusted inresponse to adjustment signal 123. The oscillator signal may beamplified by the power amplifier 124 with an amplification amountresponsive to control signal 125. The filter and matching circuit 126may be included to filter out harmonics or other unwanted frequenciesand match the impedance of the transmitter 104 to the transmit antenna114.

The receiver 108 may include a matching circuit 132 and a rectifier andswitching circuit 134 to generate a DC power output to charge a battery136 as shown in FIG. 2 or power a device coupled to the receiver (notshown). The matching circuit 132 may be included to match the impedanceof the receiver 108 to the receive antenna 118. The receiver 108 andtransmitter 104 may communicate on a separate communication channel 119(e.g., Bluetooth, zigbee, cellular, etc).

As illustrated in FIG. 3, antennas used in exemplary embodiments may beconfigured as a “loop” antenna 150, which may also be referred to hereinas a “magnetic” antenna. Loop antennas may be configured to include anair core or a physical core such as a ferrite core. Air core loopantennas may be more tolerable to extraneous physical devices placed inthe vicinity of the core. Furthermore, an air core loop antenna allowsthe placement of other components within the core area. In addition, anair core loop may more readily enable placement of the receive antenna118 (FIG. 2) within a plane of the transmit antenna 114 (FIG. 2) wherethe coupled-mode region of the transmit antenna 114 (FIG. 2) may be morepowerful.

As stated, efficient transfer of energy between the transmitter 104 andreceiver 108 occurs during matched or nearly matched resonance betweenthe transmitter 104 and the receiver 108. However, even when resonancebetween the transmitter 104 and receiver 108 are not matched, energy maybe transferred at a lower efficiency. Transfer of energy occurs bycoupling energy from the near-field of the transmitting antenna to thereceiving antenna residing in the neighborhood where this near-field isestablished rather than propagating the energy from the transmittingantenna into free space.

The resonant frequency of the loop or magnetic antennas is based on theinductance and capacitance. Inductance in a loop antenna is generallysimply the inductance created by the loop, whereas, capacitance isgenerally added to the loop antenna's inductance to create a resonantstructure at a desired resonant frequency. As a non-limiting example,capacitor 152 and capacitor 154 may be added to the antenna to create aresonant circuit that generates resonant signal 156. Accordingly, forlarger diameter loop antennas, the size of capacitance needed to induceresonance decreases as the diameter or inductance of the loop increases.Furthermore, as the diameter of the loop or magnetic antenna increases,the efficient energy transfer area of the near-field increases. Ofcourse, other resonant circuits are possible. As another non-limitingexample, a capacitor may be placed in parallel between the two terminalsof the loop antenna. In addition, those of ordinary skill in the artwill recognize that for transmit antennas the resonant signal 156 may bean input to the loop antenna 150.

Exemplary embodiments of the invention include coupling power betweentwo antennas that are in the near-fields of each other. As stated, thenear-field is an area around the antenna in which electromagnetic fieldsexist but may not propagate or radiate away from the antenna. They aretypically confined to a volume that is near the physical volume of theantenna. In the exemplary embodiments of the invention, magnetic typeantennas such as single and multi-turn loop antennas are used for bothtransmit (Tx) and receive (Rx) antenna systems since magnetic near-fieldamplitudes tend to be higher for magnetic type antennas in comparison tothe electric near-fields of an electric-type antenna (e.g., a smalldipole). This allows for potentially higher coupling between the pair.Furthermore, “electric” antennas (e.g., dipoles and monopoles) or acombination of magnetic and electric antennas is also contemplated.

The Tx antenna can be operated at a frequency that is low enough andwith an antenna size that is large enough to achieve good coupling(e.g., >−4 dB) to a small Rx antenna at significantly larger distancesthan allowed by far field and inductive approaches mentioned earlier. Ifthe Tx antenna is sized correctly, high coupling levels (e.g., −2 to −4dB) can be achieved when the Rx antenna on a host device is placedwithin a coupling-mode region (i.e., in the near-field) of the driven Txloop antenna.

FIG. 4 is a simplified block diagram of a transmitter 200, in accordancewith an exemplary embodiment of the present invention. The transmitter200 includes transmit circuitry 202 and a transmit antenna 204.Generally, transmit circuitry 202 provides RF power to the transmitantenna 204 by providing an oscillating signal resulting in generationof near-field energy about the transmit antenna 204. By way of example,transmitter 200 may operate at the 13.56 MHz ISM band.

Exemplary transmit circuitry 202 includes a fixed impedance matchingcircuit 206 for matching the impedance of the transmit circuitry 202(e.g., 50 ohms) to the transmit antenna 204 and a low pass filter (LPF)208 configured to reduce harmonic emissions to levels to preventself-jamming of devices coupled to receivers 108 (FIG. 1). Otherexemplary embodiments may include different filter topologies, includingbut not limited to, notch filters that attenuate specific frequencieswhile passing others and may include an adaptive impedance match, thatcan be varied based on measurable transmit metrics, such as output powerto the antenna or DC current draw by the power amplifier. Transmitcircuitry 202 further includes a power amplifier 210 configured to drivean RF signal as determined by an oscillator 212. The transmit circuitrymay be comprised of discrete devices or circuits, or alternately, may becomprised of an integrated assembly. An exemplary RF power output fromtransmit antenna 204 may be on the order of 2.5 Watts.

Transmit circuitry 202 further includes a controller 214 for enablingthe oscillator 212 during transmit phases (or duty cycles) for specificreceivers, for adjusting the frequency of the oscillator, and foradjusting the output power level for implementing a communicationprotocol for interacting with neighboring devices through their attachedreceivers.

The transmit circuitry 202 may further include a load sensing circuit216 for detecting the presence or absence of active receivers in thevicinity of the near-field generated by transmit antenna 204. By way ofexample, a load sensing circuit 216 monitors the current flowing to thepower amplifier 210, which is affected by the presence or absence ofactive receivers in the vicinity of the near-field generated by transmitantenna 204. Detection of changes to the loading on the power amplifier210 are monitored by controller 214 for use in determining whether toenable the oscillator 212 for transmitting energy to communicate with anactive receiver.

Transmit antenna 204 may be implemented as an antenna strip with thethickness, width and metal type selected to keep resistive losses low.In a conventional implementation, the transmit antenna 204 can generallybe configured for association with a larger structure such as a table,mat, lamp or other less portable configuration. Accordingly, thetransmit antenna 204 generally will not need “turns” in order to be of apractical dimension. An exemplary implementation of a transmit antenna204 may be “electrically small” (i.e., fraction of the wavelength) andtuned to resonate at lower usable frequencies by using capacitors todefine the resonant frequency. In an exemplary application where thetransmit antenna 204 may be larger in diameter, or length of side if asquare loop, (e.g., 0.50 meters) relative to the receive antenna, thetransmit antenna 204 will not necessarily need a large number of turnsto obtain a reasonable capacitance.

The transmitter 200 may gather and track information about thewhereabouts and status of receiver devices that may be associated withthe transmitter 200. Thus, the transmitter circuitry 202 may include apresence detector 280, an enclosed detector 290, or a combinationthereof, connected to the controller 214 (also referred to as aprocessor herein). The controller 214 may adjust an amount of powerdelivered by the amplifier 210 in response to presence signals from thepresence detector 280 and the enclosed detector 290. The transmitter mayreceive power through a number of power sources, such as, for example,an AC-DC converter (not shown) to convert conventional AC power presentin a building, a DC-DC converter (not shown) to convert a conventionalDC power source to a voltage suitable for the transmitter 200, ordirectly from a conventional DC power source (not shown).

As a non-limiting example, the presence detector 280 may be a motiondetector utilized to sense the initial presence of a device to becharged that is inserted into the coverage area of the transmitter.After detection, the transmitter may be turned on and the RF powerreceived by the device may be used to toggle a switch on the Rx devicein a pre-determined manner, which in turn results in changes to thedriving point impedance of the transmitter.

As another non-limiting example, the presence detector 280 may be adetector capable of detecting a human, for example, by infrareddetection, motion detection, or other suitable means. In some exemplaryembodiments, there may be regulations limiting the amount of power thata transmit antenna may transmit at a specific frequency. In some cases,these regulations are meant to protect humans from electromagneticradiation. However, there may be environments where transmit antennasare placed in areas not occupied by humans, or occupied infrequently byhumans, such as, for example, garages, factory floors, shops, and thelike. If these environments are free from humans, it may be permissibleto increase the power output of the transmit antennas above the normalpower restrictions regulations. In other words, the controller 214 mayadjust the power output of the transmit antenna 204 to a regulatorylevel or lower in response to human presence and adjust the power outputof the transmit antenna 204 to a level above the regulatory level when ahuman is outside a regulatory distance from the electromagnetic field ofthe transmit antenna 204.

As a non-limiting example, the enclosed detector 290 (may also bereferred to herein as an enclosed compartment detector or an enclosedspace detector) may be a device such as a sense switch for determiningwhen an enclosure is in a closed or open state. When a transmitter is inan enclosure that is in an enclosed state, a power level of thetransmitter may be increased.

In exemplary embodiments, a method by which the transmitter 200 does notremain on indefinitely may be used. In this case, the transmitter 200may be programmed to shut off after a user-determined amount of time.This feature prevents the transmitter 200, notably the power amplifier210, from running long after the wireless devices in its perimeter arefully charged. This event may be due to the failure of the circuit todetect the signal sent from either the repeater or the receive coil thata device is fully charged. To prevent the transmitter 200 fromautomatically shutting down if another device is placed in itsperimeter, the transmitter 200 automatic shut off feature may beactivated only after a set period of lack of motion detected in itsperimeter. The user may be able to determine the inactivity timeinterval, and change it as desired. As a non-limiting example, the timeinterval may be longer than that needed to fully charge a specific typeof wireless device under the assumption of the device being initiallyfully discharged.

FIG. 5 is a simplified block diagram of a receiver 300, in accordancewith an exemplary embodiment of the present invention. The receiver 300includes receive circuitry 302 and a receive antenna 304. Receiver 300further couples to device 350 for providing received power thereto. Itshould be noted that receiver 300 is illustrated as being external todevice 350 but may be integrated into device 350. Generally, energy ispropagated wirelessly to receive antenna 304 and then coupled throughreceive circuitry 302 to device 350.

Receive antenna 304 is tuned to resonate at the same frequency, or nearthe same frequency, as transmit antenna 204 (FIG. 4). Receive antenna304 may be similarly dimensioned with transmit antenna 204 or may bedifferently sized based upon the dimensions of the associated device350. By way of example, device 350 may be a portable electronic devicehaving diametric or length dimension smaller that the diameter of lengthof transmit antenna 204. In such an example, receive antenna 304 may beimplemented as a multi-turn antenna in order to reduce the capacitancevalue of a tuning capacitor (not shown) and increase the receiveantenna's impedance. By way of example, receive antenna 304 may beplaced around the substantial circumference of device 350 in order tomaximize the antenna diameter and reduce the number of loop turns (i.e.,windings) of the receive antenna and the inter-winding capacitance.

Receive circuitry 302 provides an impedance match to the receive antenna304. Receive circuitry 302 includes power conversion circuitry 306 forconverting a received RF energy source into charging power for use bydevice 350. Power conversion circuitry 306 includes an RF-to-DCconverter 308 and may also in include a DC-to-DC converter 310. RF-to-DCconverter 308 rectifies the RF energy signal received at receive antenna304 into a non-alternating power while DC-to-DC converter 310 convertsthe rectified RF energy signal into an energy potential (e.g., voltage)that is compatible with device 350. Various RF-to-DC converters arecontemplated, including partial and full rectifiers, regulators,bridges, doublers, as well as linear and switching converters.

Receive circuitry 302 may further include switching circuitry 312 forconnecting receive antenna 304 to the power conversion circuitry 306 oralternatively for disconnecting the power conversion circuitry 306.Disconnecting receive antenna 304 from power conversion circuitry 306not only suspends charging of device 350, but also changes the “load” as“seen” by the transmitter 200 (FIG. 2).

As disclosed above, transmitter 200 includes load sensing circuit 216which detects fluctuations in the bias current provided to transmitterpower amplifier 210. Accordingly, transmitter 200 has a mechanism fordetermining when receivers are present in the transmitter's near-field.

When multiple receivers 300 are present in a transmitter's near-field,it may be desirable to time-multiplex the loading and unloading of oneor more receivers to enable other receivers to more efficiently coupleto the transmitter. A receiver may also be cloaked in order to eliminatecoupling to other nearby receivers or to reduce loading on nearbytransmitters. This “unloading” of a receiver is also known herein as a“cloaking” Furthermore, this switching between unloading and loadingcontrolled by receiver 300 and detected by transmitter 200 provides acommunication mechanism from receiver 300 to transmitter 200 as isexplained more fully below. Additionally, a protocol can be associatedwith the switching which enables the sending of a message from receiver300 to transmitter 200. By way of example, a switching speed may be onthe order of 100 μsec.

In an exemplary embodiment, communication between the transmitter andthe receiver refers to a device sensing and charging control mechanism,rather than conventional two-way communication. In other words, thetransmitter uses on/off keying of the transmitted signal to adjustwhether energy is available in the near-filed. The receivers interpretthese changes in energy as a message from the transmitter. From thereceiver side, the receiver uses tuning and de-tuning of the receiveantenna to adjust how much power is being accepted from the near-field.The transmitter can detect this difference in power used from thenear-field and interpret these changes as a message from the receiver.

Receive circuitry 302 may further include signaling detector and beaconcircuitry 314 used to identify received energy fluctuations, which maycorrespond to informational signaling from the transmitter to thereceiver. Furthermore, signaling and beacon circuitry 314 may also beused to detect the transmission of a reduced RF signal energy (i.e., abeacon signal) and to rectify the reduced RF signal energy into anominal power for awakening either un-powered or power-depleted circuitswithin receive circuitry 302 in order to configure receive circuitry 302for wireless charging.

Receive circuitry 302 further includes processor 316 for coordinatingthe processes of receiver 300 described herein including the control ofswitching circuitry 312 described herein. Cloaking of receiver 300 mayalso occur upon the occurrence of other events including detection of anexternal wired charging source (e.g., wall/USB power) providing chargingpower to device 350. Processor 316, in addition to controlling thecloaking of the receiver, may also monitor beacon circuitry 314 todetermine a beacon state and extract messages sent from the transmitter.Processor 316 may also adjust DC-to-DC converter 310 for improvedperformance.

FIG. 6 shows a simplified schematic of a portion of transmit circuitryfor carrying out messaging between a transmitter and a receiver. In someexemplary embodiments of the present invention, a means forcommunication may be enabled between the transmitter and the receiver.In FIG. 6 a power amplifier 210 drives the transmit antenna 204 togenerate the radiated field. The power amplifier is driven by a carriersignal 220 that is oscillating at a desired frequency for the transmitantenna 204. A transmit modulation signal 224 is used to control theoutput of the power amplifier 210.

The transmit circuitry can send signals to receivers by using an ON/OFFkeying process on the power amplifier 210. In other words, when thetransmit modulation signal 224 is asserted, the power amplifier 210 willdrive the frequency of the carrier signal 220 out on the transmitantenna 204. When the transmit modulation signal 224 is negated, thepower amplifier will not drive out any frequency on the transmit antenna204.

The transmit circuitry of FIG. 6 also includes a load sensing circuit216 that supplies power to the power amplifier 210 and generates areceive signal 235 output. In the load sensing circuit 216 a voltagedrop across resistor R_(s) develops between the power in signal 226 andthe power supply 228 to the power amplifier 210. Any change in the powerconsumed by the power amplifier 210 will cause a change in the voltagedrop that will be amplified by differential amplifier 230. When thetransmit antenna is in coupled mode with a receive antenna in a receiver(not shown in FIG. 6) the amount of current drawn by the power amplifier210 will change. In other words, if no coupled mode resonance exist forthe transmit antenna 204, the power required to drive the radiated fieldwill be a first amount. If a coupled mode resonance exists, the amountof power consumed by the power amplifier 210 will go up because much ofthe power is being coupled into the receive antenna. Thus, the receivesignal 235 can indicate the presence of a receive antenna coupled to thetransmit antenna 235 and can also detect signals sent from the receiveantenna. Additionally, a change in receiver current draw will beobservable in the transmitter's power amplifier current draw, and thischange can be used to detect signals from the receive antennas.

Details of some exemplary embodiments for cloaking signals, beaconsignals, and circuits for generating these signals can be seen in U.S.Utility patent application Ser. No. 12/249,873, entitled “REVERSE LINKSIGNALING VIA RECEIVE ANTENNA IMPEDANCE MODULATION” filed on Oct. 10,2008; and in U.S. Utility patent application Ser. No. 12/249,861,entitled “TRANSMIT POWER CONTROL FOR A WIRELESS CHARGING SYSTEM” filedon Oct. 10, 2008, both herein incorporated by reference in theirentirety.

Details of exemplary communication mechanisms and protocols can be seenin U.S. Utility patent application Ser. No. 12/249,866 entitled“SIGNALING CHARGING IN WIRELESS POWER ENVIRONMENT” filed on Oct. 10,2008, the contents of which is incorporated by reference herein in itsentirety.

FIGS. 7-17 illustrate a host device 400 having transmit circuitry (e.g.,transmit circuitry 202 of FIG. 4) and at least one transmit antenna 402operably coupled thereto and configured to wirelessly transmit powerwithin an associated near-field region. It is noted that transmitcircuitry and associated one or more transmit antennas may also bereferred to herein as a “charging apparatus,” a “charging platform,” ora “host device peripheral.” Accordingly, the host device peripheral isconfigured to couple to a host device. Although host device 400 isdepicted as a laptop computer in FIGS. 7-17, embodiments of the presentinvention are not so limited. Rather, host device 400 may comprise anyknown and suitable electronic device.

Transmit antenna 402 may be coupled to host device 400 in any suitablemanner and at any suitable position. For example, as illustrated inFIGS. 7 and 8, transmit antenna 402 may be coupled to a cover 408(illustrated in each of FIGS. 7 and 8 as being in an “open” position) ofhost device 400. More specifically, with reference to FIG. 7, transmitantenna 402 may be positioned adjacent a surface 406 of cover 408,wherein surface 406 is opposite a surface having a display screen (notshown). As another example, as illustrated in FIG. 8, transmit antenna402 may be positioned around and adjacent another surface 410 of cover408, wherein surface 410 is substantially perpendicular to each ofsurface 406 and a surface having a display screen (not shown). As yetanother example, as illustrated in FIG. 9, transmit antenna 402 may bepositioned adjacent a surface 412 of a base 414 of host device 400,wherein surface 412 may be adjacent to a keyboard 416 of host device400. It is noted that transmit antenna 402 may be coupled to host device400 in a manner so as to avoid any electrical interference betweentransmit antenna 402 and any metallic components of host device 400(e.g., a metallic display of host device 400). It is further noted thatalthough FIGS. 7-9 illustrate host device 400 having a single transmitantenna coupled thereto, embodiments of the present invention are not solimited. Rather, a host device having a plurality of transmit antennasis within the scope of the present invention.

FIG. 10 illustrates host device 400 having transmit antenna 402 coupledthereto and positioned adjacent surface 406 of cover 408, which isdepicted in FIG. 10 as being in a “closed” position. Furthermore, anelectronic device 420 may be positioned on surface 406 and within anear-filed region of transmit antenna 402 and, therefore, may receivepower wirelessly transmitted by transmit antenna 402. More specifically,power transmitted from transmit antenna 402 may be received by receiveantenna (e.g., receive antenna 118 of FIG. 2) and a receiver (e.g.,receiver 108 of FIG. 2), which is coupled to electronic device 420. Itis noted that the term “electronic device” as used herein may comprise achargeable device having a chargeable battery or may comprise a deviceconfigured to be independently powered by wireless power.

FIG. 11 illustrates host device 400 including an attachment device 422configured to enable one or more electronic devices, such as electronicdevice 420, to be mechanically attached to cover 408 of host device 400and positioned within a near-field of transmit antenna 402. For exampleonly, attachment device 422 may comprise a strap configured to attach toeach of cover 408 and electronic device 420 and, therefore, attach cover408 and electronic device 420 together. As another example, electronicdevice 420 may include a clip or a snap (not shown) configured to attachto attachment device 422, which is coupled to cover 408. As yet anotherexample, each of cover 408 and electronic device 420 may include aVelcro® pad to enable cover 408 and electronic device 420 to be attachedtogether. Further, as illustrated in FIG. 12, host device 400 mayinclude a pocket 424 positioned proximate cover 408 and configured tohold one or more electronic devices, such as electronic device 420,proximate cover 408 and within a near-field of transmit antenna 402.Additionally, as illustrated in FIG. 13, one or more electronic devices,such as electronic device 420, may be positioned on surface 412 of base414 and within a near-field region of transmit antenna 402, which ispositioned adjacent surface 412.

FIGS. 14 and 15 illustrate a charging pad 426 attached to host device400. Specifically, FIG. 14 illustrates charging pad 426 positionedadjacent surface 406 (see FIG. 7) of cover 408. Further, FIG. 15illustrates charging pad 426 in a folded down position remote fromsurface 406. According to one exemplary embodiment, charging pad 426 maybe attached to host device 400 in a manner to enable charging pad 426 topivot about base 414 of host device 400. More specifically, charging pad426 may be configured to pivot about base 414 in a manner similar to,but independent of, cover 408. According to another exemplaryembodiment, charging pad 426 may be configured to slide out from andretract into a portion of host device 400. Furthermore, charging pad 426may comprise a transmit antenna 403 coupled to and configured to receivepower from host device 400. As illustrated in FIG. 15, electronic device420 may be positioned on an inner surface (i.e., a surface configured toabut surface 406) of charging pad 426 and may receive power wirelesslytransmitted from transmit antenna 403. It is noted that electronicdevice 420 may also be positioned on an outer surface (i.e., a surfaceopposite a surface configured to abut surface 406) of charging pad 426and may receive power wirelessly transmitted from transmit antenna 403.

FIGS. 16 and 17 each illustrate a charging system 500 including acharging pad 502 configured to operably couple to and receive power froma power source (e.g., host device 400). More specifically, charging pad502 may include one or more transmit antennas 503 operably coupledthereto and may be configured for operable coupling to a power source(e.g., host device 400) via an electrical connector 506. As anon-limiting example, electrical connector 506 may comprise a removablepower cord configured to couple to an electrical connector (e.g., a USBport or an external power plug) of host device 400. FIG. 16 illustratescharging pad 502 electrically decoupled from host device 400 and FIG. 17illustrates charging pad 502 electrically coupled to host device 400 viaelectrical connector 506. Although charging pad 502 is illustrated as aplanar charging pad, embodiments of the present invention are not solimited. Rather, charging pads having any shape, including threedimensional objects, are within a scope of the present invention.Further, as illustrated in FIG. 17, one or more electronic devices(e.g., electronic device 420) may be positioned on a surface of chargingpad 502 and may receive power wirelessly transmitted from transmitantenna 503.

FIG. 18 illustrates a portable host device peripheral 550, in accordancewith another exemplary embodiment of the present invention. Host deviceperipheral 550 may include both a wireless power transmitter (e.g.,transmitter 200 of FIG. 4) and a wireless power receiver (e.g., receiver300 of FIG. 5). Accordingly, host device peripheral 550 may includededicated transmit and receive circuitry and at least one antenna 551configured to wirelessly transmit power within an associated near-fieldregion. It is noted that transmit and receive circuitry along withassociated antennas may be referred to herein as a “wireless powercharging apparatus.” As a result, host device peripheral 550 may beconfigured for bidirectional wireless charging, namely, the capabilityto both receive wireless power and to transmit wireless power. Anexemplary approach for such bidirectional wireless charging is describedin U.S. patent application Ser. No. 12/552,110, entitled “BIDIRECTIONALWIRELESS POWER TRANSMISSION” filed on Sep. 1, 2009, the details of whichare incorporated by reference herein. Wireless power device 550 mayfurther comprise an energy storage device 552, which may comprise, forexample only, a chargeable battery, a storage capacitor, a MEMS energystorage device, or any combination thereof.

In accordance with an exemplary embodiment, host device peripheral 550is configured to couple to a host device. For example, host deviceperipheral 550 may be configured for both electrical and mechanicalcoupling to a host device, such as, for example only, a computer. Forexample only, with reference to FIG. 19, host device peripheral 550 maybe configured for insertion (depicted by arrow 555) within a standardcavity 554 (e.g., a drive bay) of an electronic device 556, which mayalso be referred to herein as a “host device.” As a more specificexample, host device peripheral 550 may be configured to be positionedwithin and attached to a drive bay of a laptop computer. Further, aswill be understood by a person having ordinary skill in the art, a drivebay (e.g., cavity 554) may include an electrical port configured toelectrically couple a device (e.g., wireless power device 550)positioned therein to an energy storage device 558 via an electricalconnector 562. For example only, energy storage device 558 may comprisea chargeable battery, a storage capacitor, a MEMS energy storage device,or any combination thereof. It is noted that, according to one exemplaryembodiment, host device peripheral 550 may be integrated within anelectronic device. According to another exemplary embodiment, asmentioned above, host device peripheral 550 may configured to beinserted within and detachable from a host device.

FIG. 20 illustrates a wireless system 560 having host device peripheral550 positioned within cavity 554 of electronic device 556. Further, asillustrated, host device peripheral 550 may be operably coupled toenergy storage device 558 via electrical connector 562. Moreover,according to one exemplary embodiment, wireless system 560 may include apower source 565 external to electronic device 556 and configured toconvey power to electronic device 556 via electrical connector 566. Forexample only, power source 565 may comprise a power outlet. In theexemplary embodiment depicted in FIG. 20, host device peripheral 550 maybe configured to receive power via electrical connectors 566 and 562.Further, upon receipt of power, wireless power device 550 may beconfigured to store power within energy storage device 552 (see FIG.18). According to another exemplary embodiment, as illustrated in FIG.21, another wireless system 561 may include a transmit antenna 553configured to wireless transmit power, which may be received by antenna551 (see FIG. 16) of host device peripheral 550. Upon receipt of power,host device peripheral 550 may be configured to store power withinenergy storage device 552 (see FIG. 18), convey power to energy storagedevice 558, or any combination thereof. Additionally, as illustrated inFIG. 22, in an exemplary embodiment wherein host device peripheral 550is decoupled from an host device (e.g., electronic device 556), hostdevice peripheral 550 may be configured to wirelessly receive power fromtransmit antenna 553 and store power within energy storage device 552.

As illustrated in FIG. 23, and in accordance with another exemplaryembodiment, host device peripheral 550 may include a deployable portion564. Accordingly, upon positioning host device peripheral 550 withincavity 554 of electronic device 556, portion 564 may be configured toretract out (i.e., deploy in an outward direction) from electronicdevice 556. Stated another way, portion 564 of host device peripheral550 may eject from electronic device 556 in similar manner as a portionof CD drive or a portion DVD drive would “eject” from an associatedcomputer. It is noted that portion 564 of host device peripheral 550 mayinclude antenna 551 (see FIG. 18). Accordingly, portion 564 of hostdevice peripheral 550 may be configured to wireless transmit power toanother electronic device (e.g., a mobile telephone) positioned within anear-field region of antenna 551. It is noted that portion 564 mayinclude a surface configured for positioning one or more electronicdevices thereon. Providing a charging device configured for insertionwithin a host structure and having a deployable portion configured forwirelessly transmitting power may reduce undesired coupling between awireless antenna coupled to the portion and the host structure.

In accordance with an exemplary embodiment illustrated in FIG. 24, hostdevice peripheral 550 may be configured to receive power from powersource 565, energy storage device 558, energy storage device 552 (seeFIG. 18), or any combination thereof, and wireless transmit power to oneor more electronic devices 570, which are positioned within anassociated near-field region of antenna 551 (see FIG. 18). Morespecifically, for example only, host device peripheral 550 may beconfigured to wireless transmit power to one or more electronic devices570 that are positioned on a surface of portion 564. Further, accordingto another exemplary embodiment depicted in FIG. 25, host deviceperipheral 550 may be configured to receive power from transmit antenna553, energy storage device 558, energy storage device 552 (see FIG. 18),or any combination thereof, and wireless transmit power to one or moreelectronic devices 570, which are positioned within an associatednear-field region of antenna 551 (see FIG. 18). Further, in theexemplary embodiment depicted in FIG. 25, wireless power device may beconfigured to convey power received from transmit antenna 553 to energystorage device 558, energy storage device 552 (see FIG. 18), or anycombination thereof.

Moreover, in an exemplary embodiment illustrated in FIG. 26, host deviceperipheral 550 may be configured to wirelessly transmit power stored inenergy storage device 552 (see FIG. 18) to one or more electronicdevices 570, provide power to energy storage device 558, or anycombination thereof. Furthermore, as illustrated in FIG. 27, host deviceperipheral 550, which is depicted as being decoupled from an electronicdevice (i.e., electronic device 556), may wireless transmit power storedin energy storage device 552 (see FIG. 18) to one or more electronicdevices 570 positioned within a near-field region of antenna 551.Additionally, with reference to FIG. 28, host device peripheral 550,which is depicted as being decoupled from an electronic device (i.e.,electronic device 556), may be configured to receive power from transmitantenna 553, energy storage device 552 (see FIG. 18), or any combinationthereof, and wireless transmit power to one or more electronic devices570, which are positioned within an associated near-field region ofantenna 551. Furthermore, in the exemplary embodiment depicted in FIG.28, power wirelessly transmitted from transmit antenna 553 may be storedwithin energy storage device 552.

FIG. 29 is a flowchart illustrating a method 680, in accordance with oneor more exemplary embodiments. Method 680 may include electricallycoupling a host device peripheral to a host device (depicted by numeral682). Method 680 may further include transmitting power from the hostdevice peripheral to at least one chargeable battery (depicted bynumeral 684).

As will be understood by one of ordinary skill in the art, electronicdevices, such as a charging device, may be configured to operate invarious modes such as, for example only, an “active” mode, a “standby”mode, a “sleep” mode, or a “charging” mode. Moreover, as will also beunderstood by one of ordinary skill in the art, while operating in apower saving mode (e.g., a “standby” mode or a “sleep” mode), aconventional charging device may not be configured to detect thepresence of an electronic device positioned proximate or coupledthereto.

In accordance with an exemplary embodiment of the present invention, acharging device may be configured detect an electronic device andtransition from a power saving mode to a charging mode upon detection ofthe electronic device. More specifically, a charging apparatus or device(e.g., electronic device 400 illustrated in FIGS. 7-17) may beconfigured to detect the presence of an electronic device (e.g.,electronic device 420 of FIG. 10) while operating in a power savingmode. Yet, even more specifically, while operating in a power savingmode such as, for example only, a “standby” mode, a “sleep” mode, or anycombination thereof, the charging device may be configured to detect thepresence of an electronic device, either positioned within an associatednear-field region or coupled thereto via a wired connection.

For example only, the presence of an electronic device may be detectedvia near-field communication between a transmit antenna (e.g., transmitantenna 402; see FIG. 7) of the charging device and an antenna (notshown) within the electronic device and configured for receivingwireless power. As another example, the charging device may beconfigured to detect the presence of a radio-frequency identification(RFID) tag connected to the electronic device. As yet another example,the charging device may be configured to detect the presence of theelectronic device upon the electronic device being electrically coupledto the charging device via a wired connector.

FIG. 30 illustrates a state machine diagram 900 for a charging deviceconfigured for detecting the presence of an electronic device whileoperating in a power saving mode. Furthermore, a state machine diagram902 of a transmitter (e.g., transmitter 202 of FIG. 4) associated withthe charging device is also illustrated in FIG. 30. According to oneexemplary embodiment as illustrated in FIG. 30, while the chargingdevice operates in a power saving mode 910, the associated transmittermay remain in a normal operating state 912 and, therefore, may beconfigured to, according to any known and suitable method, detect thepresence of an electronic device being positioned within an associatednear-field region. Upon detection of an electronic device, the chargingdevice may transition from power saving mode 910 to a charging mode 916.

FIG. 31 illustrates another state machine diagram 920 for a chargingdevice configured for detecting the presence of an electronic devicewhile operating in a power saving mode. Furthermore, a state machinediagram 922 of a transmitter (e.g., transmitter 202 of FIG. 4)associated with the charging device is also illustrated in FIG. 31.According to another exemplary embodiment, while operating in a powersaving mode 924, the charging device may be configured to periodicallyenter into a “detection” state wherein the associated transmitter maytemporarily transition from a power saving mode 930 into a normaloperating state 932. Accordingly, while in normal operating state 932,the transmitter may, according to any known and suitable method, detectthe presence of an electronic device being positioned within anassociated near-field region. Upon detection of an electronic device,the charging device may transition from power saving mode 924 to acharging mode 926.

FIG. 32 is a flowchart illustrating another method 690, according to oneor more exemplary embodiments. Method 690 may include detecting at leastone electronic device with a charging device (depicted by numeral 692).Furthermore, method 690 may include switching the charging device from apower saving mode to a charging mode upon detection of the at least oneelectronic device (depicted by numeral 694).

Those of skill in the art would understand that information and signalsmay be represented using any of a variety of different technologies andtechniques. For example, data, instructions, commands, information,signals, bits, symbols, and chips that may be referenced throughout theabove description may be represented by voltages, currents,electromagnetic waves, magnetic fields or particles, optical fields orparticles, or any combination thereof.

Those of skill would further appreciate that the various illustrativelogical blocks, modules, circuits, and algorithm steps described inconnection with the exemplary embodiments disclosed herein may beimplemented as electronic hardware, computer software, or combinationsof both. To clearly illustrate this interchangeability of hardware andsoftware, various illustrative components, blocks, modules, circuits,and steps have been described above generally in terms of theirfunctionality. Whether such functionality is implemented as hardware orsoftware depends upon the particular application and design constraintsimposed on the overall system. Skilled artisans may implement thedescribed functionality in varying ways for each particular application,but such implementation decisions should not be interpreted as causing adeparture from the scope of the exemplary embodiments of the invention.

The various illustrative logical blocks, modules, and circuits describedin connection with the exemplary embodiments disclosed herein may beimplemented or performed with a general purpose processor, a DigitalSignal Processor (DSP), an Application Specific Integrated Circuit(ASIC), a Field Programmable Gate Array (FPGA) or other programmablelogic device, discrete gate or transistor logic, discrete hardwarecomponents, or any combination thereof designed to perform the functionsdescribed herein. A general purpose processor may be a microprocessor,but in the alternative, the processor may be any conventional processor,controller, microcontroller, or state machine. A processor may also beimplemented as a combination of computing devices, e.g., a combinationof a DSP and a microprocessor, a plurality of microprocessors, one ormore microprocessors in conjunction with a DSP core, or any other suchconfiguration.

The steps of a method or algorithm described in connection with theexemplary embodiments disclosed herein may be embodied directly inhardware, in a software module executed by a processor, or in acombination of the two. A software module may reside in Random AccessMemory (RAM), flash memory, Read Only Memory (ROM), ElectricallyProgrammable ROM (EPROM), Electrically Erasable Programmable ROM(EEPROM), registers, hard disk, a removable disk, a CD-ROM, or any otherform of storage medium known in the art. An exemplary storage medium iscoupled to the processor such that the processor can read informationfrom, and write information to, the storage medium. In the alternative,the storage medium may be integral to the processor. The processor andthe storage medium may reside in an ASIC. The ASIC may reside in a userterminal. In the alternative, the processor and the storage medium mayreside as discrete components in a user terminal.

In one or more exemplary embodiments, the functions described may beimplemented in hardware, software, firmware, or any combination thereof.If implemented in software, the functions may be stored on ortransmitted over as one or more instructions or code on acomputer-readable medium. Computer-readable media includes both computerstorage media and communication media including any medium thatfacilitates transfer of a computer program from one place to another. Astorage media may be any available media that can be accessed by acomputer. By way of example, and not limitation, such computer-readablemedia can comprise RAM, ROM, EEPROM, CD-ROM or other optical diskstorage, magnetic disk storage or other magnetic storage devices, or anyother medium that can be used to carry or store desired program code inthe form of instructions or data structures and that can be accessed bya computer. Also, any connection is properly termed a computer-readablemedium. For example, if the software is transmitted from a website,server, or other remote source using a coaxial cable, fiber optic cable,twisted pair, digital subscriber line (DSL), or wireless technologiessuch as infrared, radio, and microwave, then the coaxial cable, fiberoptic cable, twisted pair, DSL, or wireless technologies such asinfrared, radio, and microwave are included in the definition of medium.Disk and disc, as used herein, includes compact disc (CD), laser disc,optical disc, digital versatile disc (DVD), floppy disk and blu-ray discwhere disks usually reproduce data magnetically, while discs reproducedata optically with lasers. Combinations of the above should also beincluded within the scope of computer-readable media.

The previous description of the disclosed exemplary embodiments isprovided to enable any person skilled in the art to make or use thepresent invention. Various modifications to these exemplary embodimentswill be readily apparent to those skilled in the art, and the genericprinciples defined herein may be applied to other embodiments withoutdeparting from the spirit or scope of the invention. Thus, the presentinvention is not intended to be limited to the exemplary embodimentsshown herein but is to be accorded the widest scope consistent with theprinciples and novel features disclosed herein.

What is claimed is:
 1. An apparatus for wireless power charging,comprising: a receive circuit configured to wirelessly receive power andcharge an energy storage device using the wirelessly received power; anda charging device configured to charge an electronic device in acharging mode, the charging device comprising a transmit circuitconfigured to: receive power from the energy storage device andwirelessly transmit the received power to the electronic device, anddetect a presence or an absence of the electronic device positionedwithin a wireless field of the transmit circuit while the transmitcircuit is operating in a normal operating state, wherein the chargingdevice is further configured to transition to the charging mode from apower savings mode to charge the electronic device when the presence ofthe electronic device is detected by the transmit circuit and remain inthe power savings mode if the absence of the electronic device isdetected by the transmit circuit.
 2. The apparatus of claim 1, whereinthe transmit circuit and the receive circuit are configured to bepositioned within a cavity of a host device comprising the energystorage device.
 3. The apparatus of claim 2, wherein the cavitycomprises a drive bay.
 4. The apparatus of claim 2, wherein the hostdevice comprises a laptop computer.
 5. The apparatus of claim 1, whereinthe energy storage device is configured to receive power from anexternal power source, and wherein the transmit circuit is furtherconfigured to receive power from the energy storage device using theexternal power source.
 6. The apparatus of claim 1, wherein the transmitcircuit and the receive circuit form a peripheral device.
 7. Theapparatus of claim 1, wherein the transmit circuit and the receivecircuit are integrated into a peripheral device, the peripheral deviceintegrated into a host device comprising the energy storage device. 8.The apparatus of claim 1, wherein the transmit circuit and the receivecircuit are integrated into a host device comprising the energy storagedevice.
 9. The apparatus of claim 1, further comprising a portionconfigured to extend from a host device comprising the energy storagedevice, the portion comprising a loop antenna coupled to the transmitand receive circuits.
 10. The apparatus of claim 1, wherein the transmitcircuit and the receive circuit are detachable from a host devicecomprising the energy storage device.
 11. The apparatus of claim 1,further comprising a loop antenna, wherein the loop antenna is coupledto an outside surface of a host device comprising the energy storagedevice.
 12. The apparatus of claim 11, further comprising an attachmentdevice coupled to the outside surface of the host device, the attachmentdevice configured to attach an electronic device to the outside surfaceof the host device.
 13. The apparatus of claim 11, further comprising areceptacle coupled to the outside surface of the host device, thereceptacle configured to receive and secure an electronic device. 14.The apparatus of claim 11, wherein the loop antenna is coupled to aportion of a cover of the host device.
 15. The apparatus of claim 11,wherein the loop antenna is configured to be placed substantially arounda circumference of a portion of the host device, the circumferencedetermined by an outer dimension of the host device.
 16. The apparatusof claim 11, wherein the loop antenna is characterized by a shapeforming a square.
 17. The apparatus of claim 11, wherein the loopantenna is characterized by a shape conforming to a shape determined byan outer dimension of the host device.
 18. The apparatus of claim 1,further comprising a charging pad, the charging pad comprising thetransmit circuit and the receive circuit.
 19. The apparatus of claim 1,wherein the transmit circuit and the receive circuit are configured tomechanically couple to a host device comprising the energy storagedevice, the transmit circuit and the receiver circuit further configuredto pivot about a base of the host device.
 20. The apparatus of claim 1,wherein the transmit circuit and the receive circuit are located withina portion of a host device and are configured to deploy therefrom andreturn into the portion of the host device.
 21. The apparatus of claim1, further comprising a loop antenna, wherein the loop antenna iscoupled to a surface of a base of a host device comprising the energystorage device.
 22. The apparatus of claim 1, wherein the energy storagedevice comprises a chargeable battery.
 23. The apparatus of claim 1,wherein the transmit circuit and the receive circuit form a peripheraldevice detachable from a host device comprising the energy storagedevice.
 24. The apparatus of claim 1, wherein the transmit circuit andthe receive circuit for a peripheral device configured to mechanicallycouple to a host device comprising the energy storage device.
 25. Theapparatus of claim 1, wherein the transmit circuit and the receivecircuit form a peripheral device located within a portion of a hostdevice, wherein the peripheral device is configured to deploy therefromand return into the portion of the host device.
 26. A method,comprising: wirelessly receiving power via a wireless field; charging anenergy storage device with power received wirelessly; receiving powerfrom the energy storage device; wirelessly transmitting power to anelectronic device via a transmit circuit; detecting a presence or anabsence of the electronic device positioned within a wireless field ofthe transmit circuit while the transmit circuit is operating in a normaloperating state; transitioning a charging device comprising the transmitcircuit to a charging mode from a power saving mode when the presence ofthe electronic device is detected by the transmit circuit; remaining inthe power savings mode if the absence of the electronic device isdetected; and charging the electronic device when the charging devicetransitions to the charging mode.
 27. The method of claim 26, furthercomprising mechanically coupling the transmit circuit within a cavity ofa host device comprising the energy storage device.
 28. The method ofclaim 27, further comprising deploying a portion comprising a loopantenna to extend from the host device.
 29. The method of claim 26,wherein wirelessly transmitting power to an electronic device compriseswirelessly transmitting power to an electronic device positioned on asurface coupled to the transmit circuit.
 30. The method of claim 26,wherein detecting comprises detecting the presence or the absence of theelectronic device via near-field communication.
 31. The method of claim26, wherein detecting comprises detecting a radio-frequencyidentification (RFID) tag connected to the electronic device.
 32. Themethod of claim 26, wherein transitioning the charging device from thepower savings mode to the charging mode comprises transitioning thecharging device from at least one of a standby mode and a sleep mode tothe charging mode.
 33. The method of claim 26, further comprisingmechanically coupling the transmit circuit as a peripheral device withina cavity of a host device comprising the energy storage device.
 34. Anapparatus for wireless power charging, comprising: means for wirelesslyreceiving power; means for charging an energy storage device using thewirelessly received power; means for receiving power from the energystorage device; means for wirelessly transmitting the received power toan electronic device; means for charging the electronic devicecomprising the means for wirelessly transmitting; and means fordetecting a presence or an absence of the electronic device positionedwithin a wireless field of the means for wirelessly transmitting whileoperating the means for wirelessly transmitting in a normal operatingstate, wherein the means for charging is configured to: transition froma power savings mode to a charging mode when the means for detectingdetects the presence of the electronic device positioned within thewireless field, remain in the power savings mode when the means fordetecting detects the absence of the electronic device positioned withinthe wireless field, and charge the electronic device when in thecharging mode.
 35. The apparatus of claim 34, further comprising meansfor mechanically coupling the means for wirelessly transmitting and themeans for wirelessly receiving within a cavity of a host devicecomprising the energy storage device.
 36. The apparatus of claim 35,wherein the cavity comprises a drive bay.
 37. The apparatus of claim 34,further comprising means for deploying a portion to extend from a hostdevice comprising the energy storage device, the portion comprising aloop antenna coupled to the means for wirelessly transmitting and themeans for wirelessly receiving.
 38. The apparatus of claim 34, whereinthe means for wirelessly transmitting power to an electronic devicecomprises means for wirelessly transmitting power to an electronicdevice positioned on a surface coupled to the means for wirelesslytransmitting and the means for wirelessly receiving.
 39. The apparatusof claim 34, wherein the means for detecting comprises means fordetecting the presence or the absence of the electronic device vianear-field communication.
 40. The apparatus of claim 34, wherein themeans for detecting comprises detecting a radio-frequency identification(RFID) tag connected to the electronic device.
 41. The apparatus ofclaim 34, wherein the means for charging being configured to transitionfrom a power savings mode to a charging mode comprises being configuredto transition from at least one of a standby mode and a sleep mode tothe charging mode.
 42. The apparatus of claim 34, further comprisingmeans for receiving power from an external power source.
 43. Theapparatus of claim 34, wherein the means for wirelessly transmitting andthe means for wirelessly receiving are integrated into a host devicecomprising the energy storage device.
 44. The apparatus of claim 34,further comprising means for detaching the means for wirelesslytransmitting and the means for wirelessly receiving from a host devicecomprising the energy storage device.
 45. The apparatus of claim 34,further comprising means for coupling a loop antenna to an outsidesurface of a host device comprising the energy storage device.
 46. Theapparatus of claim 45, further comprising means for attaching anelectronic device to the outside surface of the host device.
 47. Theapparatus of claim 46, wherein the means for attaching comprises areceptacle coupled to the outside surface of the host device, thereceptacle configured for placement of the electronic device.
 48. Theapparatus of claim 34, further comprising means for coupling a loopantenna to a portion of a cover of a host device comprising the energystorage device.
 49. The apparatus of claim 34, wherein the means forwirelessly transmitting and the means for wirelessly receiving areconfigured to be positioned within a charging pad.
 50. The apparatus ofclaim 34, further comprising means for mechanically coupling the meansfor wirelessly transmitting and the means for wirelessly receiving tothe a device comprising the energy storage device and means for pivotingthe means for wirelessly transmitting and the means for wirelesslyreceiving about a base of the host device.
 51. The apparatus of claim34, further comprising means for deploying the means for wirelesslytransmitting and the means for wirelessly receiving out from andreturning the means for wirelessly transmitting and the means forwirelessly receiving into a portion of a host device comprising theenergy storage device.
 52. The apparatus of claim 34, further comprisingmeans for coupling a loop antenna to a surface of a base of a hostdevice comprising the energy storage device.
 53. The apparatus of claim34, further comprising means for positioning a loop antennasubstantially around a circumference of a portion of the means forwirelessly transmitting and the means for wirelessly receiving, thecircumference determined by an outer dimension of the means forwirelessly transmitting and the means for wirelessly receiving.
 54. Theapparatus of claim 34, further comprising a loop antenna characterizedby a shape forming a square.
 55. The apparatus of claim 34, furthercomprising a loop antenna characterized by a shape conforming to a shapedetermined by an outer dimension of the means for wirelesslytransmitting and the means for wirelessly receiving.
 56. The apparatusof claim 34, wherein the energy storage device comprises a chargeablebattery.
 57. The apparatus of claim 34, wherein the energy storagedevice is configured to be positioned within a laptop computer.
 58. Theapparatus of claim 34, further comprising means for mechanicallycoupling the means for wirelessly transmitting and the means forwirelessly receiving as a peripheral device within a cavity of a hostdevice comprising the energy storage device.
 59. The apparatus of claim34, further comprising means for detaching the means for wirelesslytransmitting and the means for wirelessly receiving from a host devicecomprising the energy storage device, wherein the means for wirelesslytransmitted and the means for wirelessly receiving form a peripheraldevice.
 60. The apparatus of claim 34, further comprising means fordeploying a peripheral device comprising the means for wirelesslytransmitting and the means for wirelessly receiving out from andreturning the peripheral device into a portion of a host devicecomprising the energy storage device.